New pole contribution to $P_{h\perp }$-weighted single-transverse spin asymmetry in semi-inclusive deep inelastic scattering

Abstract

In this paper, we discuss the new hard pole contribution to the $P_{h\perp }$-weighted single-transverse spin asymmetry in semi-inclusive deep inelastic scattering. We perform the complete next-to-leading order calculation of the $P_{h\perp }$-weighted cross section and show that the new hard pole contribution is required in order to obtain the complete evolution equation for the Qiu-Sterman function derived by different approaches.

Comments: 19 pages, 6 figures